fix(usage): close the QA findings on opt-in product usage

A QA exploration of this branch against an isolated rig — own stub
collector, SQLite and PostgreSQL — turned up one dead end and a set of
signals and controls that did not hold up. This closes all of them.

Rotating JWT_SECRET, the documented response to a suspected compromise,
made the signing key unreadable. That was already named and documented,
but it left no way out: the delete packet can never be signed, so the
row stays deletion_pending forever, and enable() refuses because it is
not `disabled`. An operator who rotated precisely because the secret was
compromised cannot restore it, so the feature was bricked with no
control left. POST /usage/abandon is offered only in that state; it
drops the local identity and records the receipt as
`collector-unconfirmed` rather than claiming a deletion that did not
happen.

Every failed delivery was retried on the next admin request, and
/activity is open to any authenticated admin while the settings ticker
fires it every five minutes per open tab — 30 activity calls against a
rejecting collector produced 30 outbound requests. Migration 206 adds
attempts/next_attempt_at and the unattended sender honours the gate;
Retry and opt-out still send immediately, and the tab names the time of
the next automatic attempt.

Feedback, votes and portal sessions now share an installation-wide
budget of 30/hour. They are the only endpoints whose effect is outbound
traffic carrying operator-written free text, and the general limiter
skips authenticated requests by design. Reading status and withdrawing
stay unthrottled.

gallery_image_protection was true on a bare install with no galleries:
PicPeak ships default_protection_level='standard' and
enable_devtools_protection=true, so it reported fleet-wide 100% and
could never separate a decision from an untouched default. It now reads
only what deviates from the shipped defaults, and the devtools flag is
not read at all — being on by default, its only informative state is
off, which is the opposite of what the key claims.

Also:
- the export receipt counted every packet and called the total "usage
  reports"; reports and participant operations are now counted and named
  separately
- GET /usage/preview no longer persists the custom_css marker, so the
  transparency view stops changing what will be sent
- the feedback route requires every field the packet schema requires,
  so an API caller gets the missing field named instead of a bare
  INVALID_PACKET from inside signing
- the German strings for this feature use "Sie" throughout, matching the
  rest of the admin UI; the ignore hint says what ignoring will do
  rather than stating it as already true
- the consent dialog returns focus to the control that opened it
- the long buttons wrap instead of running off a 390px viewport
- a deletion receipt is labelled as belonging to an earlier
  participation while a new one is active

Regression tests cover each of these, including the delete packet's
reuse of the last accepted sequence, which was an unwritten assumption
about the collector rather than a defect.

backend/__tests__/services/usageEnableDisableRace.test.js

@@ -57,6 +57,8 @@ async function bootDb() {
     t.string('lease_token', 36);
     t.bigInteger('lease_until').notNullable().defaultTo(0);
     t.bigInteger('cancel_seq').notNullable().defaultTo(0);
+    t.integer('attempts').notNullable().defaultTo(0);
+    t.bigInteger('next_attempt_at').notNullable().defaultTo(0);
   });
   await db.schema.createTable('product_usage_markers', (t) => {
     t.string('feature', 60).primary();

backend/__tests__/services/usageExportReceipt.test.js

@@ -0,0 +1,147 @@
+/**
+ * Two things the participant is entitled to have stated exactly.
+ *
+ * The export receipt is a privacy document — the artefact an operator shows a
+ * third party — so a count in it has to mean what its label says. It counted
+ * every packet in the participation (feedback, votes, portal sessions, the
+ * registration) and called the total "usage reports": an install that had sent
+ * one report and twenty feedback items reported twenty-one reports.
+ *
+ * The delete packet's sequence is the other: it reuses the last ACCEPTED
+ * sequence rather than taking the next one, unlike every other action. That is
+ * a contract with the collector, not an implementation detail — if the
+ * collector ever enforced strictly increasing sequences per installation, the
+ * withdrawal would be rejected forever and the operator could never leave. It
+ * is pinned here so the assumption is written down and a change to it has to
+ * be deliberate.
+ */
+const knex = require('knex');
+const { UsageService } = require('../../src/usage/UsageService');
+const { generateIdentity, verifyEnvelope } = require('../../src/usage/protocol.cjs');
+
+const SECRET = 's'.repeat(48);
+
+async function bootDb() {
+  const db = knex({
+    client: 'sqlite3',
+    connection: { filename: ':memory:' },
+    useNullAsDefault: true,
+  });
+  await db.schema.createTable('product_usage_state', (t) => {
+    t.integer('id').primary();
+    t.string('status', 30).notNullable().defaultTo('disabled');
+    t.string('consent_version', 40).notNullable().defaultTo('usage-consent.v2');
+    t.boolean('notice_dismissed').notNullable().defaultTo(false);
+    t.string('installation_id', 64);
+    t.string('public_key', 59);
+    t.text('private_key_encrypted');
+    t.string('instance_binding', 64);
+    t.bigInteger('sequence').notNullable().defaultTo(0);
+    t.text('pending_packet');
+    t.text('last_packet');
+    t.text('last_receipt');
+    t.text('privacy_receipts');
+    t.string('last_report_date', 10);
+    t.string('last_error', 80);
+    t.text('feedback_preferences');
+    t.string('lease_token', 36);
+    t.bigInteger('lease_until').notNullable().defaultTo(0);
+    t.bigInteger('cancel_seq').notNullable().defaultTo(0);
+    t.integer('attempts').notNullable().defaultTo(0);
+    t.bigInteger('next_attempt_at').notNullable().defaultTo(0);
+  });
+  await db('product_usage_state').insert({ id: 1 });
+  await db.schema.createTable('product_usage_markers', (t) => t.string('feature', 60).primary());
+  return db;
+}
+
+const envelope = (action) => ({ packet: { action, installation_id: 'a'.repeat(64) } });
+
+describe('the export receipt states what it actually counted', () => {
+  let db;
+  afterEach(async () => { if (db) await db.destroy(); db = null; });
+
+  const exportWith = async (packets) => {
+    db = await bootDb();
+    await db('product_usage_state').where({ id: 1 }).update({
+      status: 'active',
+      installation_id: 'a'.repeat(64),
+    });
+    const service = new UsageService(db, {
+      secret: SECRET,
+      endpoint: 'https://usage.example.test',
+      now: () => Date.parse('2026-09-06T12:00:00.000Z'),
+      fetch: async () => ({
+        ok: true,
+        headers: { get: () => null },
+        body: (async function* () {
+          yield Buffer.from(JSON.stringify({ installation_id: 'a'.repeat(64), packets }));
+        })(),
+      }),
+    });
+    await service.export();
+    return JSON.parse((await db('product_usage_state').where({ id: 1 }).first()).privacy_receipts)
+      .last_export;
+  };
+
+  it('counts reports as reports and everything else separately', async () => {
+    const receipt = await exportWith([
+      envelope('register'),
+      envelope('report'),
+      envelope('consent'),
+      envelope('feedback'),
+      envelope('feedback'),
+      envelope('vote'),
+      envelope('session'),
+    ]);
+    expect(receipt.report_count).toBe(1);
+    expect(receipt.packet_count).toBe(7);
+    expect(receipt.scope).toEqual([
+      'accepted usage reports',
+      'accepted participant operations',
+    ]);
+  });
+
+  it('reports zero rather than a total when no report was ever accepted', async () => {
+    const receipt = await exportWith([envelope('register'), envelope('feedback')]);
+    expect(receipt.report_count).toBe(0);
+    expect(receipt.packet_count).toBe(2);
+  });
+});
+
+describe('the delete packet reuses the last accepted sequence', () => {
+  let db;
+  afterEach(async () => { if (db) await db.destroy(); db = null; });
+
+  it('sends the accepted sequence, not the next one', async () => {
+    db = await bootDb();
+    const identity = generateIdentity();
+    const sent = [];
+    const service = new UsageService(db, {
+      secret: SECRET,
+      endpoint: 'https://usage.example.test',
+      now: () => Date.parse('2026-09-06T12:00:00.000Z'),
+      bindingPath: `${require('os').tmpdir()}/usage-delete-seq-${Date.now()}.key`,
+      fetch: async (_url, options) => {
+        const body = JSON.parse(options.body);
+        sent.push(verifyEnvelope(body, Date.parse('2026-09-06T12:00:00.000Z')));
+        // Deliberately not a sequence-enforcing collector: this test pins what
+        // PicPeak sends, and the collector contract is what must match it.
+        throw new Error('stop after capturing the packet');
+      },
+    });
+    await db('product_usage_state').where({ id: 1 }).update({
+      status: 'deletion_pending',
+      installation_id: identity.installation_id,
+      public_key: identity.public_key,
+      private_key_encrypted: service.encrypt(identity.private_key),
+      sequence: 7,
+    });
+
+    await service.tick({ force: true });
+
+    expect(sent).toHaveLength(1);
+    expect(sent[0].action).toBe('delete');
+    expect(sent[0].sequence).toBe(7);
+  });
+});

backend/__tests__/services/usageServiceKeyRotation.test.js

@@ -10,6 +10,7 @@
  */
 const knex = require('knex');
 const { UsageService } = require('../../src/usage/UsageService');
+const { generateIdentity, makePacket } = require('../../src/usage/protocol.cjs');
 
 const SECRET_A = 'a'.repeat(48);
 const SECRET_B = 'b'.repeat(48);
@@ -39,6 +40,8 @@ async function bootDb() {
     t.text('feedback_preferences');
     t.string('lease_token', 36);
     t.bigInteger('lease_until').notNullable().defaultTo(0);
+    t.integer('attempts').notNullable().defaultTo(0);
+    t.bigInteger('next_attempt_at').notNullable().defaultTo(0);
   });
   await db('product_usage_state').insert({ id: 1 });
   return db;
@@ -94,3 +97,166 @@ describe('usage signing key becomes unreadable after secret rotation', () => {
     expect(row.status).toBe('active');
   });
 });
+
+/**
+ * Naming the failure told the operator what happened but left them nowhere to
+ * go: the delete packet can never be signed, so the row stays in
+ * deletion_pending forever, and enable() refuses because it is not `disabled`.
+ * An operator who rotated the secret precisely because it was compromised
+ * cannot restore it, so without an exit the feature is bricked.
+ */
+describe('abandoning a withdrawal that can never be signed', () => {
+  let db;
+  afterEach(async () => { if (db) await db.destroy(); db = null; });
+
+  const stuck = async () => {
+    db = await bootDb();
+    await db.schema.createTable('product_usage_markers', (t) => {
+      t.string('feature', 60).primary();
+    });
+    await db('product_usage_markers').insert({ feature: 'crm' });
+    await db('product_usage_state').where({ id: 1 }).update({
+      status: 'deletion_pending',
+      installation_id: 'a'.repeat(64),
+      public_key: 'p'.repeat(59),
+      private_key_encrypted: new UsageService(db, { secret: SECRET_A }).encrypt('key'),
+      sequence: 4,
+      last_error: 'SIGNING_KEY_UNREADABLE',
+    });
+    return new UsageService(db, {
+      secret: SECRET_B,
+      endpoint: 'https://usage.example.test',
+      bindingPath: `${require('os').tmpdir()}/usage-abandon-${Date.now()}.key`,
+      fetch: () => { throw new Error('network must not be reached'); },
+    });
+  };
+
+  it('clears the local identity and records the deletion as unconfirmed', async () => {
+    const service = await stuck();
+    const status = await service.abandon();
+
+    expect(status.status).toBe('disabled');
+    expect(status.installation_id).toBeNull();
+    const row = await db('product_usage_state').where({ id: 1 }).first();
+    expect(row.private_key_encrypted).toBeNull();
+    expect(row.public_key).toBeNull();
+    expect(row.last_error).toBeNull();
+    expect(await db('product_usage_markers').count('* as c').first()).toEqual({ c: 0 });
+
+    // The receipt must not claim a deletion the collector never confirmed.
+    const receipt = JSON.parse(row.privacy_receipts).last_abandonment;
+    expect(receipt.status).toBe('collector-unconfirmed');
+    expect(receipt.reason).toBe('SIGNING_KEY_UNREADABLE');
+    expect(receipt.installation_id).toBe('a'.repeat(64));
+  });
+
+  it('lets the operator rejoin afterwards', async () => {
+    const service = await stuck();
+    await service.abandon();
+    expect((await service.state()).status).toBe('disabled');
+  });
+
+  it('refuses on a withdrawal that is merely undelivered', async () => {
+    const service = await stuck();
+    await db('product_usage_state').where({ id: 1 }).update({ last_error: 'DELIVERY_FAILED' });
+    await expect(service.abandon()).rejects.toThrow(/abandoned/);
+    expect((await service.state()).installation_id).toBe('a'.repeat(64));
+  });
+
+  it('refuses while participation is active', async () => {
+    const service = await stuck();
+    await db('product_usage_state').where({ id: 1 }).update({ status: 'active' });
+    await expect(service.abandon()).rejects.toThrow(/abandoned/);
+    expect((await service.state()).installation_id).toBe('a'.repeat(64));
+  });
+});
+
+/**
+ * Every failed delivery used to be retried on the next admin request, and
+ * /activity is open to any authenticated admin while the settings ticker fires
+ * it every five minutes per open tab. A permanently rejected packet therefore
+ * produced one collector request per admin action, indefinitely.
+ */
+describe('delivery backoff', () => {
+  let db;
+  afterEach(async () => { if (db) await db.destroy(); db = null; });
+
+  // A real identity and a schema-valid packet, so the failure happens where
+  // this test claims it does — at the network — rather than in signPacket.
+  const activeWithPendingPacket = async (fetchImpl, now) => {
+    db = await bootDb();
+    await db.schema.createTable('product_usage_markers', (t) => {
+      t.string('feature', 60).primary();
+    });
+    const service = new UsageService(db, {
+      secret: SECRET_A,
+      endpoint: 'https://usage.example.test',
+      now: () => now(),
+      fetch: fetchImpl,
+    });
+    const identity = generateIdentity();
+    await db('product_usage_state').where({ id: 1 }).update({
+      status: 'active',
+      consent_version: 'usage-consent.v2',
+      installation_id: identity.installation_id,
+      public_key: identity.public_key,
+      private_key_encrypted: service.encrypt(identity.private_key),
+      sequence: 1,
+      pending_packet: JSON.stringify(
+        makePacket(identity, 'session', 2, {}, 'usage.v2')
+      ),
+    });
+    return service;
+  };
+
+  it('paces the next unattended attempt after a failure, and lets Retry skip it', async () => {
+    let clock = 1_000_000;
+    let calls = 0;
+    const service = await activeWithPendingPacket(() => {
+      calls += 1;
+      throw new Error('collector unreachable');
+    }, () => clock);
+
+    await service.tick();
+    expect(calls).toBe(1);
+    const paced = await service.state();
+    expect(Number(paced.attempts)).toBe(1);
+    expect(Number(paced.next_attempt_at)).toBeGreaterThan(clock);
+
+    // The unattended callers — /activity and the settings ticker — wait.
+    await service.tick();
+    await service.tick();
+    expect(calls).toBe(1);
+
+    // The operator pressing Retry does not.
+    await service.tick({ force: true });
+    expect(calls).toBe(2);
+    expect(Number((await service.state()).attempts)).toBe(2);
+
+    // Once the window passes, the automatic sender tries again on its own.
+    clock = Number((await service.state()).next_attempt_at) + 1;
+    await service.tick();
+    expect(calls).toBe(3);
+  });
+
+  it('grows the wait with consecutive failures and caps it at an hour', () => {
+    const service = new UsageService(null, { secret: SECRET_A, endpoint: 'https://usage.example.test' });
+    expect(service.backoffMs(1)).toBe(2 * 60000);
+    expect(service.backoffMs(3)).toBe(8 * 60000);
+    expect(service.backoffMs(20)).toBe(60 * 60000);
+  });
+
+  it('clears the pacing once a packet is accepted', async () => {
+    const clock = 1_000_000;
+    const service = await activeWithPendingPacket(async () => {
+      throw new Error('collector unreachable');
+    }, () => clock);
+    await service.tick();
+    expect(Number((await service.state()).attempts)).toBe(1);
+
+    await service.clearDeliveryBackoff();
+    const cleared = await service.state();
+    expect(Number(cleared.attempts)).toBe(0);
+    expect(Number(cleared.next_attempt_at)).toBe(0);
+  });
+});

backend/__tests__/services/usageSnapshotSignals.test.js

@@ -34,6 +34,8 @@ async function bootDb() {
     t.text('feedback_preferences'); t.string('lease_token', 36);
     t.bigInteger('lease_until').notNullable().defaultTo(0);
     t.bigInteger('cancel_seq').notNullable().defaultTo(0);
+    t.integer('attempts').notNullable().defaultTo(0);
+    t.bigInteger('next_attempt_at').notNullable().defaultTo(0);
   });
   await db('product_usage_state').insert({ id: 1 });
   await db.schema.createTable('product_usage_markers', (t) => t.string('feature', 60).primary());
@@ -196,6 +198,116 @@ describe('S3 use is only implied by backups that write to the destination', () =
   });
 });
 
+/**
+ * A signal whose answer is fixed by the shipped defaults is not a signal.
+ * PicPeak ships default_protection_level='standard' and
+ * enable_devtools_protection=true, so accepting either as evidence made
+ * gallery_image_protection true on a bare install with no galleries — a
+ * fleet-wide 100% that cannot separate a decision from an untouched default.
+ */
+describe('gallery_image_protection reports decisions, not shipped defaults', () => {
+  let db;
+  afterEach(async () => { if (db) await db.destroy(); db = null; });
+
+  const v2 = async () => {
+    db = await bootDb();
+    await db.schema.alterTable('events', (t) => {
+      for (const column of ['disable_right_click', 'enable_devtools_protection', 'use_canvas_rendering']) t.boolean(column);
+      t.string('protection_level');
+    });
+    await db('product_usage_state').where({ id: 1 })
+      .update({ status: 'active', consent_version: 'usage-consent.v2' });
+    return service(db);
+  };
+  const shipped = async () => {
+    // Exactly what migration 038 seeds, plus an event carrying the column
+    // defaults from the same migration.
+    await db('app_settings').insert([
+      { setting_key: 'default_protection_level', setting_value: '"standard"' },
+      { setting_key: 'enable_devtools_protection', setting_value: 'true' },
+      { setting_key: 'enable_canvas_rendering', setting_value: 'false' },
+    ]);
+    await db('events').insert({
+      protection_level: 'standard',
+      enable_devtools_protection: true,
+      use_canvas_rendering: false,
+      disable_right_click: false,
+    });
+  };
+
+  it('is false on a bare install with no galleries at all', async () => {
+    const client = await v2();
+    expect((await client.snapshot()).features.gallery_image_protection)
+      .toEqual({ configured: false });
+  });
+
+  it('is false when every value is still the shipped default', async () => {
+    const client = await v2();
+    await shipped();
+    expect((await client.snapshot()).features.gallery_image_protection)
+      .toEqual({ configured: false });
+  });
+
+  it('ignores the devtools flag entirely, since it ships on', async () => {
+    const client = await v2();
+    await shipped();
+    // Turning it OFF is the only informative state it has, and that is the
+    // opposite of what this key claims — so neither state may set it.
+    await db('app_settings').where({ setting_key: 'enable_devtools_protection' })
+      .update({ setting_value: 'false' });
+    await db('events').update({ enable_devtools_protection: false });
+    expect((await client.snapshot()).features.gallery_image_protection)
+      .toEqual({ configured: false });
+  });
+
+  it.each([
+    ['a stronger global level', async (db) => db('app_settings').where({ setting_key: 'default_protection_level' }).update({ setting_value: '"maximum"' })],
+    ['global canvas rendering', async (db) => db('app_settings').where({ setting_key: 'enable_canvas_rendering' }).update({ setting_value: 'true' })],
+    ['a stronger level on one gallery', async (db) => db('events').update({ protection_level: 'enhanced' })],
+    ['canvas rendering on one gallery', async (db) => db('events').update({ use_canvas_rendering: true })],
+    ['right-click disabled on one gallery', async (db) => db('events').update({ disable_right_click: true })],
+  ])('is true for %s', async (_label, change) => {
+    const client = await v2();
+    await shipped();
+    await change(db);
+    expect((await client.snapshot()).features.gallery_image_protection)
+      .toEqual({ configured: true });
+  });
+});
+
+/**
+ * The settings preview is the "see exactly what would be sent" view. It shared
+ * snapshot() with the real sender, and snapshot() records applied custom CSS
+ * as a lifetime marker — so reading the transparency view wrote a marker.
+ */
+describe('preview does not change what will be sent', () => {
+  let db;
+  afterEach(async () => { if (db) await db.destroy(); db = null; });
+
+  const withAppliedCss = async () => {
+    db = await bootDb();
+    await db('product_usage_state').where({ id: 1 })
+      .update({ status: 'active', consent_version: 'usage-consent.v2' });
+    await db('app_settings').insert({
+      setting_key: 'general_custom_css', setting_value: '".x{}"'
+    });
+    return service(db);
+  };
+
+  it('reports custom_css as used without persisting the marker', async () => {
+    const client = await withAppliedCss();
+    const preview = await client.preview();
+    expect(preview.features.custom_css).toEqual({ configured: true, used: true });
+    expect(await db('product_usage_markers').pluck('feature')).toEqual([]);
+  });
+
+  it('still persists it when the sender builds the real report', async () => {
+    const client = await withAppliedCss();
+    await client.snapshot();
+    expect(await db('product_usage_markers').pluck('feature')).toEqual(['custom_css']);
+  });
+});
+
 describe('v2 technical configuration and privacy boundaries', () => {
   let db;
   let savedEnv;